Michelle, 34, revealed news of her son Aaron's condition on Sunday, tweeting fans to keep them updated.
"The last 24 hours have been the worst and scariest in my life," she said. "With everything I've been through mentally and physically, nothing, I mean nothing, compares to that of when your baby is sick.
"Our beautiful baby boy has been very looked after in hospital after being diagnosed with viral meningitis. And reflux disease just to top it off.
"He's fighting strong & taking the antibiotics well so far… But at only 5 weeks old one can only imagine our @hughhanley distress as parents.
"He's very sick and in pain with the reflux. The hospital are amazing and he's well looked after. Hopefully we will be able to take our little man home soon. I'm sure we will."
Michelle welcomed little Aaron Jay, her second child with husband Hugh Hanley, on 28 February. The couple are also parents to two-year-old daughter Faith.
Michelle made the brave decision to have a double mastectomy in November 2012 after being diagnosed with a mutated BRCA gene. Following Aaron's arrival, she is now planning to have her ovaries removed as a preventative measure against cancer.
"I'd be risking my life if I had another baby," she said back in December. "No matter how daunting it is having my ovaries out, it's necessary."